Make mining fee policy match relay fee policy.

This resolves a case in which a mismatch could be used to bloat up the
mempool by sending transactions that pay enough fee to relay, but not
to be mined, with the default policies.

src/main.cpp

@@ -51,7 +51,7 @@ unsigned int nCoinCacheSize = 5000;
 
 /** Fees smaller than this (in satoshi) are considered zero fee (for transaction creation) */
 int64_t CTransaction::nMinTxFee = 10000;  // Override with -mintxfee
-/** Fees smaller than this (in satoshi) are considered zero fee (for relaying) */
+/** Fees smaller than this (in satoshi) are considered zero fee (for relaying and mining) */
 int64_t CTransaction::nMinRelayTxFee = 1000;
 
 static CMedianFilter<int> cPeerBlockCounts(8, 0); // Amount of blocks that other nodes claim to have

src/main.h

@@ -35,8 +35,9 @@ class CInv;
 
 /** The maximum allowed size for a serialized block, in bytes (network rule) */
 static const unsigned int MAX_BLOCK_SIZE = 1000000;
-/** Default for -blockmaxsize, maximum size for mined blocks **/
+/** Default for -blockmaxsize and -blockminsize, which control the range of sizes the mining code will create **/
 static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
+static const unsigned int DEFAULT_BLOCK_MIN_SIZE = 0;
 /** Default for -blockprioritysize, maximum space for zero/low-fee transactions **/
 static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 50000;
 /** The maximum size for transactions we're willing to relay/mine */

src/miner.cpp

@@ -136,7 +136,7 @@ CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
 
     // Minimum block size you want to create; block will be filled with free transactions
     // until there are no more or the block reaches this size:
-    unsigned int nBlockMinSize = GetArg("-blockminsize", 0);
+    unsigned int nBlockMinSize = GetArg("-blockminsize", DEFAULT_BLOCK_MIN_SIZE);
     nBlockMinSize = std::min(nBlockMaxSize, nBlockMinSize);
 
     // Collect memory pool transactions into the block
@@ -254,7 +254,7 @@ CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
                 continue;
 
             // Skip free transactions if we're past the minimum block size:
-            if (fSortedByFee && (dFeePerKb < CTransaction::nMinTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
+            if (fSortedByFee && (dFeePerKb < CTransaction::nMinRelayTxFee) && (nBlockSize + nTxSize >= nBlockMinSize))
                 continue;
 
             // Prioritize by fee once past the priority size or we run out of high-priority